During switching events (e.g. hot switching), electronic switches may deviate from system characteristic impedance Zo. Impedance deviation may be referred to as an impedance glitch. A magnitude of impedance mismatch may be indicated by voltage standing wave ratio (VSWR), where a 1:1 VSWR indicates matched impedance and a VSWR higher than 1:1 indicates mismatch.
Impedance glitches slow down communication performance by temporarily disrupting data transmission and reception, pose reliability issues for numerous components and lead to a myriad of costs. Severe impedance glitches between system and switch ports during switching events may result in signal reflections and voltage and current stress that interrupt communication and/or limit the lifespan of switch components and components coupled to the switch.
Complex circuitry and/or programming are necessary to address problems caused by impedance glitches. Complex circuitry and programming incur design costs, production costs (e.g. by increasing die and circuit board area) and operating costs (e.g. by consuming power). As an example, a switch may be used to select one of several voltage-controlled oscillators (VCOs) to control a modulating frequency coupled to a system. During switching, the impedance glitch initially load-pulls the VCO being selected, which changes its output frequency and causes the phase locked loop (PLL) to unlock. When this occurs, the system is unable to communicate until the loop recovers. Sophisticated circuitry and/or firmware/software programming development are required to overcome these interruptions. In another example, switching glitches in switched-power amplifiers may be detrimental to performance or even cause damage if sophisticated circuitry and/or programming are insufficient to counteract the glitches.
Mitigation of impedance glitches may reduce switch and system design, fabrication and operating costs and may improve switch and system performance and reliability.